Air supported mattresses are used with cots and beds to provide yieldable body supports. The air mattresses can be inflated with hand operated pumps or bag pumps. Motor driven blowers and pumps have also been used more effectively to supply air under pressure to air mattresses. U.S. Pat. Nos 4,908,895 and 4,644,597, assigned to the assignee of the present invention, describe possible constructions of air mattresses.
The air mattresses will typically sit within a border which supports the mattress such as that described in U.S. Pat. No. 4,991,244, also assigned to the assignee of the present invention. Double, queen or king size beds can involve two air mattresses or two air chambers with individually adjustable air pressures. These air chambers may be further divided internally with free fluid flow between these further divisions. The air mattresses can be equipped with a one-way air pressure relief valve operable to limit the air pressure in the air mattress to about 1 psig (pounds per square inch gauge, i.e., relative to ambient pressure) to prevent seam separation and blowout.
The biasing or firmness characteristics of an air mattress are determined by the pressure of the air in the air mattress. Control mechanisms have been used to adjust the inflation of air mattresses. Young et al. in U.S. Pat. No. 4,224,706, for instance, disclose a mechanism for adjusting the amount of air in an air mattress. The mechanism disclosed in the '706 patent includes one or more receptacles connected to air mattresses for supplying air to and receiving air from the air mattresses. These receptacles are located in the frame below the mattress. The internal volumes of the receptacles are changed by the rotation of a hand crank. The variation of the volume in the receptacles adjusts the pressure of the air in the air mattresses.
Other control systems for air mattresses have allowed operators to vary the air pressure within the mattress at the touch of a button. The hand control units in these systems were either located on the air tube connecting the pump to the mattress or the hand control units made an electrical connection to the pump and solenoid valves. See, for example, U.S. Pat. Nos. 4,897,890, 4,829,616, 4,890,344, also assigned to the assignee of the present invention.
These hand control units typically allowed for the transmittance of two instructions to the pump/control unit. These instructions were either to increase or to decrease the pressure. The users had to rely on their tactile senses in adjusting the air pressure because the units supplied no information to the user regarding the pressure in the mattress.
One previous design of pressure control for an air mattress involved keeping the air pressure constant at all times whether the user was on the mattress or not. See U.S. Pat. Nos. 5,142,717 and 4,995,124. A control unit allowed for a preset pressure to be set. One problem with this arrangement was the dramatic change in pressure at the time a user applied weight to the mattress. The air mattress had to have an internal structure to support much of the users weight in order to prevent the escape of large volumes of air while regulating the pressure at the previously set value. The internal structure interfered with the comfort advantages of having an air supported mattress.
Another design of a pressure control unit provided a digital display of the internal pressure and push buttons. See U.S. Pat. No. 5,020,176. The user could either use a constant pressure mode where the pressure could be set by the user. The user also had the option of using a manual mode where the pressure was not kept constant but where the user directly controlled the flow of fluid into or out from the mattress.
In these previous designs, if the bed contained two separate mattresses or air bladders, two hand control units were supplied with each controlling its respective air bladder. Therefore, a person lying on one side of the bed could not assist their bed partner on the other side of the bed with an adjustment of the air pressure on the other side of the bed without physically going to that side of the bed. The hand control units were physically attached to the control unit, thereby restricting the location of a particular unit.
The processing involved in these earlier control systems for air beds was minimal. The constant pressure systems involved a periodic examination of the pressure and a comparison with the desired value. Air was then added or removed as needed with several steps used if needed to obtain the desired pressure. In the manual control designs, the operator directly controlled the pump and the release valve to control the flow of fluid into or out of the mattress.
Electric motor driven pumps have been used in the past to inflate air mattresses. The operating noise of such pumps was a common source of consumer complaints. The pumps were most frequently utilized when the bed user was preparing to go to sleep. A noisy pump detracted from the restful atmosphere necessary to induce sleep. The most frequent cause of noisy operation of such pumps is the rigid mounting of the fan motor to the pump housing. Such rigid mounting transmits vibrations and noises generated by the pump motor to the pump housing and to the environment around the pump. Further avenues of noise transmission to the environment in air pumps are the supply air inlet and the cooling air inlet. Sound insulating and dampening materials could be built into the pump motors and housings, but only at the risk of thermal insulation and resultant over heating of the pump motors.
It would be an advantage in the industry to provide a quiet pump in which the noise and vibration of the fan motor is dampened with respect to the pump housing and wherein adequate cooling of the pump motor was provided for. Further, the air inlet and cooling air inlet should be designed to minimize the amount of fan noise transmitted therethrough. It would be an important advance to provide a multi-speed motor to provide for optimal pumping with less noise and with a minimum of overheating problems. With respect to the control of the units, it would be a distinct advantage to have hand control units where the user of the unit was not tethered to the pump unit, and where the user could control both air bladders in the case where each side of the bed had its own independent bladder. It would also be a decided advance in the art to be able to accurately and consistently monitor and control the pressure of the air mattress to a desired setting.